Electric sound reproducer



Oct, Z1, 1930. M. wEn.

v ELECTRIC souND REPRODUGER 2 Sheets-Sheet Vl Filed Oct. l, 1929 Nh. J. s, m m N R E @of d VM H Mw. QS, mf @m v r .u L QN QN NN Oct. 21, 1 930. M. wElL 1,779,223

. ELECTRIC SOUND REPRODUCER Filed Oct. 1, 1929 2 Sheets-Sheet V2 INVENTOR L', ATT RNEYJ Patented Oct. 21,`1930 4 MAXIMILIAN WEIL, or NEW Yoan, N. Y.

ELECTRIC SOUND mnonucnn Application led October 1, 1929. Serial No. 396,508.

tially proof against sticking or freezingfy of the armature thereof to a pole piece but n which shall be readily maintained in balance mechanically and electromagnetically to assure best performance.

Another object is to' provide apparatus of the above type which permits of ready removal and replacementf the magnetic pickup head, Without the need for` disconnecting the circuit of the amplifier with respect to the reproducer arm, and which facilitates the establishment of electric circuit with respect to said head, regardless of the mechanical tightness or looseness of the mounting connection between the arml and the pick-up head and in which repeated manipulation of the head for replacing' the stylus and the like, for instance, will not result in loosening .the electrical contact through which the minute currents must .pass in the operation of the instrument.

`A feature of the invention is the construction of magnetic pick-upV head in which damping meansis so -disposedand correlated with thearmature that it may beconveniently set by hand to assure magnetic balance with 0 respect to the pole pieces.- Preferably the damping means comprises ai block of gum rubber which intimately contacts both faces of an armature vane near the extremity thereof beyond the coil,v and the rubber damper is 5 so arranged that itvmay b e bodily moved by manual adjustment from the exterior of the case to balance the construction.`

In a preferred construction the rubber damper is disposed in a metal capsule which is itself connected by screws preferably to the pole pieces, and the adjustment'means may be a screw, threaded into the reproducer casing and having' a grooved connection with the capsule so that by turning this screw, the capsule may be shifted slightly for the de-v sired purpose. f

While the condition of magnetic balance may be ascertained by noting equality in volume of sound in tapping the stylus at either side, it is desirable also to provide Athe case with a scanner from whichthe central position of thel armature within the air gap between the poles may be visually ascer tained.

Another feature is the arrangement of the magnetic head as a unit, easily connected mechanically and electrically with respect to the carryin arm. For this purpose it is preferred to a ord-a ready mechanical connection and an independent relatively loose electrical connection. Any of various mechanical connections may be used, but I` prefer to pluga piloted part of the reproducer mounting bracket in the channel-end of the reproducer' arm and to secure the parts by appropriate screws. The electrical connection is preferably effected by the prong endsl of ter-vv minal wires protruding from the pick-up case and releasably plugged in a pair of electric sockets carried by the reproducer arm'. The jack .sockets are connected to conductors clamped longitudinally of the arm, preferably Within the channel and extend to near the opposite end from which they areelectrically 'connected to the amplifier.

Another feature of theinvention is the mounting means for the reproducer arm. This mounting means preferably comprises a base supporting a hub bymeans 0f a thrust bearing, the hub preferably having a horizontal axis upon which the reproducer arm is Amounted.. i 1 l In the drawings in which is shown one of various possible embodiments of the several r features of the invention. Y 95 Fig. 1 is a plan view of the reproducer arm,

Fig. 2 is a view in longitudinal cross-sec- 7 tion taken -on line 2 -2 of Fig.'1, pick-up unit in side elevation,

Figs. 3, 4, 5, 6 and are respectively trans'- with the verse cross-sectional detail views on lines 3-3, 4-4, 5 5, 6-6, and 7-7 of Fig. 2.

Fig. 8 is a plan view of the magnetic pickup illustrating the scanner device,

Fig. 9 is a plan View thereof scale with the cover removed, I

Fig. 10 is a fragmentary sectional view on line 10-10 of Fig. 11, Y

Fig. 11 is a fragmentary sectional view on line 1l-11 of Fig. lO,

Fig. 12 is a transverse sectional view on line 12-12 of Fig. 11,

Fig. 13 is 'a perspective view illustrating al preferred magnetic pole. arrangement and Fig. 14 is a perspective view of the damper unit.

Referring nowV to the drawings, there is shown a support base 20 of more or less conventional construction, which may be partly cut away interiorly as at 21 for lightness, and has fixed axially thereof an upstanding support post 22 in a depression in the upper end of which is a ball 23 aording a thrust bearing for the carrying hub 24 on which reproducer arm A is supported. The hub 24 presents a socket 25 telescoped over the ball 23 and rod 22, and has a sleeve 26 integral with the lowerend thereof, encirclingl the base 2O for free rotation threabout. A screw 27 through the sleeve 26 rides in a peripheral groove 28 about the base to prevent these elements from coming apart.

The hub 24 has an integral lateral bracket 29 with a horizontal bore affording a bearing 30 for mounting the reproducer arm A. For this purpose, the arm A which is of channel shape straddles the bracket 29 laterally.

on a larger Screws 31 and 32 inserted through corresponding apertures in the sides s of the channel arm are threaded at their inner ends into Corresponding taps 33 and 34 within the bracket 30. Set screws 35 and 36 through the lower part of the bracket 3() lock the bearing screws to the latter, so that the parts between the heads h and the bracket bearing 3()y afford the support bearing for the arm A. Preferwhich purpose for the web the latter is pro# ably the bracket 30 is provided with an up-V standing outer end 4() surmounted by a piece of felt 41 whichy yieldingl limits the downward movement of the ic -up unit U at the 'outer end of the arm Preferably the upper en d of the hub 24 extends to a level above that of the arm A, for

vided with an elongated slot 42 through which the upper end of the hub protrudes. x

The arm A is preferably so arranged as to be normally balanced in horizontal position, for which purpose a counter-weight 43 attached by screw 44 to one end thereof serves .to counterbalance the weight of thel magnetic pick-up head U secured at the other end. The counter-weight 43 is preferably disposed between the sides of the channel arm and the slot 45 for the screw 44 is elongated to permit adjustment of the weight forl correct counterbalancing."

rThe ick-up head U, the detailed construction o which will be described hereinafter,

has a bracket piece 47 secured to the casing by screws 48 and having integral therewith a pilot fiange 49 adapted snugly to pass between the sides of the channel arm A to a limiting position determined by bead 50 on the bracket. The pilot may be heldin position by a screw 51 threaded through one of the sides A of the arm and through one side of the pilot ange 49.- A short screw 52 laterally of said first screw through the opposite side s of the reproducer arm and threaded into the pilot flange acts as a stop for the bias-cut lower edge 53 of the pilot topprevent pivotal movement of the pick-up head about the screw 51.

Preferably the electrical connection from the coil C of the pick-up is independent of the mechanical mount of said unit, and in the preferred embodiment quickfdetachable with respect to the connection from the reproducer arm A to the amplifier (not shown). For this purpose,.cne of the sides s of the channel arm is preferably provided with a pair of jack sockets between the spring fingers 55 of which are releasably 'clamped the prong ends 56 of flexible wire leads 57 from the coil C. The screw 51 terminates short of the side of the pilot, to permit passing the leads 57 for clamping the same against pilot face 49, the screw serving as a cleat prevents dragging of said leads upon the record (not shown). As a precaution, a piece of insulating tubing 58 about the screw 51 insulates the'latte-r fromthe wire leads 57. y

Each of the jack sockets preferably has a bushing 59 protruding laterally from the side of the arm A, through which the prong end 56 of the wire lead is inserted, said bushing having threaded upon the inner end thereof a nut 60 which clamps the base ring 61 of the spring finger unit in position. To socket rings 6l are preferably soldered as at 62,'-fthe ends-of conductors 63 and 64 respecti'vely leading longitudinally of the arm A for-,connection to the amplifier (not shown). v .l

. For convenientmountofsaid longitudinal tn )nriectorsL'onev orinore cleats 65 are providedzgf These cleats are preferably curved in conformity with the curvature of a trough 66 l pressed into the web of the arm` A, thereby -axis and may be readily setl with respect to a record of any diameter and will travel therealong as required. The arm also has-limited and 32 in a longitudinal plane, so that the stylus S can adapt itself to the varying levels incurred inthe playing of records.

The tightness or looseness of the mechanical mount of the pickup U withrespect to the arm-A in no way affects the security or lreliability ofthe electrical connection, since the latter is established through thevgindependent leads 57.

To replace a magnetic pick-up unit, it is merely necessary partly or wholly to remove vscrews 51 and A52,'` to remove the prongs 56 from the spring fingers 55 and withdraw the unit, for which a substitute may as conveniently bel replaced. The electrical connec- -tions along the arm and from the arm to the amplifier need not be disturbed.

Thus repeated manipulation of the head for replacing the stylus, for instance, for adjustment and the like, will not result in loosening the electrical contact between the head and the arm, which contact must remain particularly intimate to assure passage of theininitesimal currents utilized inthe Voperation of the instrument.

In Figs. 8 to 13 is shown a preferred form of magnetic pick-up unit, whichxwhile preferably used on the reproducing arm and support above described may be used to advantage inother relations. The magnetic pickup unit comprises a more or less conventional case U withinl which is mounted a horse-shoe ,magnet held in place by a plate 71, se-

-cured by screws 72 threaded tol the back of the casing U. The horse-shoe magnet has associated therewith, pole 'pieces 73 and 74; of the usual magnetic metal, which in turn are secured to the case by bolts 7 5 and 76. The pole pieces have notches 77 at their inner faces, determining a case 'for the electromagnetic coil C and grooves 7 7 along which the wax used for securing the coil in place will spread. Through the coil extends the 'armature 78` which preferably-has integral gudgeon pins 79 encircled by rubber sleeves 8O disposed in corresponding cylindrical bearing support 81 between contiguous edges at the lower part of the pole pieces.f 'The armature has the usual socket 82 at its lower end for the stylus S which is retainedin'position by the usual set screw 83.

sociated with the upper end of the vane which protrudes above the air-gap. This construction is preferably a unitcomprismg a capsule including a sheet metal base piece affording asocket 90 llodging a rectangular block 91 therein, of resilient plastic material, preferably gum rubber, longltudlnally sht 84 extends with sulicient clearance lto pre' vent any engagement between said metal parts. The capsule also includes a cover tray 92 of sheet metal, the-peripheral area of which rests upon the ends 90 of the base 90. The cover may have a central opening 94 smaller than the rubber block 91 to clamp the periphery of the latter.

Ends 90. support the capsule by resting upon the pole pieces, the damper extending therefrom downwardA into depression 88 formed by corresponding notches in the upper faces of the pole pieces. The lower face of socket 90 clears the pole piece structure therebclow as shown -and the rubber is free from contact with the pole pieces at all times. The lateral flanges 95 of the cover straddle the pole piecesand the end flanges- 96 thereof extend into'notches97 in the upperl the lateral edges thereof. Both the socket piece and the cover piece have elongated slots 99 for the screws, to permit the adjustment presently to be described. lThe cover flange 96 is notched at 100 to straddle a groove 101 about a screw 102 threaded through pole piece 73and having a illister head 103 accessible .from the lateral wall of the casing U. A washer 104 of gasket material is preferably disposed under the head of the screw and a coil spring 105 encircling the screw and reacting against the pole piece 73 and the casing U normally maintains the screw in tight re, lation.

Preferably the case is provided with a scannr opening which may be covered by a sheet 110 of celluloid or other transparent material. The scanner-opening .is .direc/tly in front. of. the magnetic lair gap. The scanner opening has lateral extensions 111 which facilitate entry of light, readily reflected b the smooth metal parts within. By use o "the scanner, geometrical centering of the armature may be visually ascertaine e B vmy invention, the armature may be rea ily set for and maintained in perfectly balanced condition, with a degree of precision corresponding to that attainable in a laboratory.` For this purpose, it is preferred to balancel or calibrate the unitfrom-time to time, preferably about as often as a stringed instrument is tuned by a musician, usually pre'- paratory to each performance.

Calibration to correct balanced position is accomplished by adjusting movement of the screw-102,'with the aid of-a screw driver or coin. By this movement the floating damper capsule is displaced longitudinally in the drection of armature movement determined by the elongated slots 99, for bodily movement therewith of the gum rubber damper and with the latter of the armature. No strainis applied tothe rubber in any ysuch adjustment as might be the case were. it attempted for this purpose to slide the rubberover the fixed pole pieces or any other xed metal part. The latter operation might result in the rubber buckling rather than gliding with respect to the metallic surface, and in subsequently restor-v ing itself, the rubber would again displace the armature from balanced position. By the Calibrating action according to my invention,

not only is the quality of performance maintained at its best, but incidentally the inoperativeness due to freezing is obviated.

Inasmuch as the magnet used in apparatus of the character described is quite powerful, it is desirable to seal all openings in the case through' which small paramagnetic particles might be attracted and caused to impair the action of the apparatus. For this purpose the socket 82 is encircled by a rubber bushing 82 which may be cemented into the case, but

affords the resilience to permit vibration of the socket with its stylus. A similar bushing .83. similarly applied excludes particles from about set screw 83. Gasket 104 protects the opening for adjustment sc'reW 102 and celluloid Window 110 guards the scanner openinu.

l'Dl`he correct or balanced position of the armature can readily be determined audibly by adjustment settings. vdainper snugly engages both faces of the arance thereof. It is due to the irregularities in the construction or magnetic reluctance ofthe pole pieces etc. that geometrical centering does not in practice afford magnetic balance.

Accordingly while the scanner may be used as a primary means for ascertaining approx imate calibration of the unit, it is employed preferably only as a preliminary aid to the audible balancing method above described.

'The position of the rubber damper with respect to the armature remains the same for-all At all times the rubber mature vane and responds uniformly during playing resiliently to oppose vibration of theV armature to either side from neutral.

It will thus be seen that there 1s herein described apparatus in which the several fea-v tures of thispinvention are embodied, and which apparatus in its action attains the various objects of the invention and is well suited to meet the requirements of practical use.

above construction, and many apparently lwidely diderent embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention., what I claim as new and desire to secure by Let-A ters Patent is:

l. An electric phonograph reproducercomprising pole pieces, an armature having a pivotal mount and including `a vane substantially in the plane of the pivoting axis,

extending between and protruding beyond the. pole pieces, non-magnetic means coact- .ing with opposite faces of the protruding armature vane and resisting the movement of the latter, a rigid carrier therefor and As manyl changes could be made lin the manual means accessible from the exterior. A

of said reproducer and coacting said carrier for determining the setting of said non-magnetic means and of said armature relative to said pole pieces. y'

2. In an electric phonograph reproducer, the combination of a casing, pole pieces therein, a stylus-carrying armature extending between said pole pieces, resilient means for restraining the movement of said armature from one to the other pole, and manual operating means accessible from the exterior of said casing for bodily moving said resilient means to adjust the. position of the' armature. 3. An electric phonograph reproducer of [the type comprising a casing having pole pieces therein, and stylus-carrying. armature pivoted in said casing, having non-metallic resilient restraining means coacting with a part of said armature, a holder for saidresilient means', and manual means accessible from the exterior of said case for adjusting the position of said holder.

il. In an electric phonograph reproduce'r, the combination of magnetic'pole pieces, an armature having a pivot mount; adjacent thereto and ha`ving a part thereofextending between and adapted to come into' close con.

tiguity with surfaces of opposite poles, re-

silient restraining means for said armature n including gum rubber- .at opposite faces thereof, bracket means mounting said rubber and free of said armature, and manual adjusting means accessible from the exterior of said reproducer, and coacting with said lbracket for movement of the latter at will.

5. rAn electric phonograph reproducer comprising magnetic pole pieces, an arvmature extending therebetween, mounting means for said armature governing the movement thereof, resilient restraining means including gum rubber at opposite faces of said armature and beyond the pole pieces, a holder for said restraining means and a setting device protruding from one end of the holder and accessible from the exterior of the operating parts for adjusting the position of said holder.

6. An electric phonograph reproducer comprising magnetic pole pieces,' an armature extending therebetween, mounting -means for that of'said armature.-

said armature governing the. movement thereof, resilient restraining means including gumrubber at opposite faces of said armature and beyond the pole pieces, a holder for said restraining means, and means accessible from the exterior of thereproducer for adjustingv the position of said holder ina path of movement substantially parallel'to 7. An electric phonograph comprising a casing, polepieces therein, an

armature having a pivot axis and a vane substantially in the plane of said axis and extending between and in close contiguity to opposite poles, a gum rubber damper engaging opposite faces of said armature beyond said poles, al holder for said damper, and free from said armature, and an adjustment screw accessible from'the exterior of saidcasing having engagement with said holder, for adjusting the same to balance said armature.. v 8.- An electric phonograph reproducerl comprising pole pieces, a damper unit, an armature extending between said pole pieces Y and coacting with saiddamper unit, means fastening said damper unitwith respect to said pole pieces and settingmeans for adrior and coactingwith said carrier for adjusting the position of said damper unit while said fastening means remains in fixed position.

9. An electric phonograph reproducer` comprising pole pieces, a damper unit mounted upon said pole pieces andrbeyond -the air gap thereof, an armature extending between said vpole pieces with its extremity lprotruding into s aid damper said unit including a resilient part and a rigid carrier therefor, andv means accessible from the extejusting the position ofl said damper.

10. An electric. phonograph reproducer .p comprising a metallic capsule including a base piece and a cover dening'a cavity therebetween, a piece Vof gum rubber lodged within-saidcavity, means for slidably mounting said capsule adjacent the pole pieces and meansfor effecting adjustmnt in the poistion of said capsule.v

11.An electric phonograph reproducer comprising-a metallic capsule including a reproducerbase piecehaving a socket, a piece of gum rubber lodged within said socket, a cover piece, means slidably mounting said capsule adjacent the pole pieces, and an'adjustment screw coacting with said capsule to adjust the position thereof.

12. An electric phonograph. reproducer comprising a pair of pole pieces, an armature pivotally mounted therebetween, having 'an upstanding vane extending .beyond the air gap of said pole'pieces, adamper unit engaging the protruding end of 'the arma-` ture, said unit comprising a metallic socket, a piece of gum rubber snugly lodged therein, having a longitudinal slit-throu h which the vane extends, means securing said socket to the pole pieces and permitting limited shifting movement'thereof, to center or balance-thearmature and an adjustment screw having engagement with a portion of said socket.`

13. -An electric phonograph reproducer including -a casing, pole pieces therein, an

armature movable between said pole pieces,

means accessible from the exterior of said casing for positioning said armature, and

gap to aid in determining the balanced position of the armature.

15. As an articlel of manufacture, a damp-4 ing unit for a magnetic phonograph reproducer, said unit comprising a sheet metal socketA piece, apiece of gum rubber therein, a cover piece, elongated screw slots 1n said socket and cover pieces for slidably-securing the unit in position, one of said pieces having an inturned part for. engagement with an adjustment screw. l

16. An electric phonograph reproducer, comprising'a casing, pole pieces therein, an armature extending across 'the air gap therebetween, a gu rubber damper engaging opposite faces o the armature beyond the air gap, holder-means for said damper, manual screw adjustment means'accessible from the holder and with it saiddamp'er means, and means automatically' retaining said damper means against shifting from adjusted position. r

1 7. Aphonographf reproducer construction comprising a sup rt, a thrust bearing fixed thereto', a carryin said thrustbearing an having a pivotal hub sustained on exterior of said casing forA positioning said movement thereabout, a horizontal pivot carried by said hub, a reproducer arm bearing on said pivot, a reproducer head at one end of said arm and a counterweight at the other end of said arm.

18. A phonograph reproducer construction comprising a support, a thrust bearing fixed thereto, a carrying hub sustained on said thrust bearing and having a pivotal movement thereabout, a horizontal pivot support carried by said hub, a reproducer arm bearing on said pivot, a reproducer head connected to one end of said arm and a counterweight at the other end of said arm, said hub having a stop integral therewithvto limit the pivoting movement of the reproducer head in a downward direction.

19. A phonograph reproducer construction comprising a support, a thrust bearing fixed thereto, a carrying hub sustained on said thrust bearing-and having a pivotal movement thereabout, said hub having a horizontal pivot, a reproducer arm bearing on said latter pivot, a reproducer head connected to one end oisaid arm and a counterweight at the otherwend of said arm, the upper end of' said hub extending upward through an elongated slot in said arm.J affording clearance to permitmovement of the latter about its horizontal pivot.

20. An electric phonograph reproducer structure including a support base having an upstanding thrust bearing, ahub piece encircling said base and movable about said upstanding thrust bearing and sustained thereon, a horizontal pivot bearing carried by said hub, a reproducer arm pivotally supported on said horizontal bearing -and affording clearance for the upper end of said hub, a reproducer head at one end of said arm and a counter-balanced weight at the y. other end thereof.

21. An electric phonograph reproducer structure including a support base having an upstanding thrust bearing, a hub piece encircling said base and movable about said upstanding thrust bearing and sustained thereon, a horizontal pivot bearing carried by said hub, a reproducer arm pivotally supported on said horizontal bearing and af'- fording clearance for the upper end of said hub, said reproducer arm being ofchannel. shape, straddling vsaid pivot bearing, and means passing through said channel` and affixed to said bearing support, and constituting a bearing for said arm.

22. In an electric phonograph reproducer construction, the combination of a support.

arm, a reproducer head detachably supported rigidly with respect to the length of said 4 arm, electric terminals on said arm displaced from said head sup ort terminal conduttors on said head, free y displaceable relative theretol and plugged into the terminals on said arm.

23. In an electric phonograph reproducer, a pivoted arm, electric conductors extending longitudinally thereof, electric sockets at the ends of said conductors on said arm, a reproducer head detachably connected to the extremity of said arm and rigidly with respect `to the length thereof and flexible electric conductor terminals adapted to be releasably plugged into said sockets.

24. lin an electric phonograph reproducer, a movable. arm, a reproducer head having a detachable mechanical connection for securely retaining said head rigid with respect to the length of said arm, electric terminals on said arm and flexible electrical conductors carried by said head beyond the various parts of said head when the latter is mechanically positioned upon said arm, said flexible conductors and adapted to be releasably plugged with respect to said terminals while said head is in position upon said arm.

25. ln an electric phonograph reproducer, an arm having a pivot near one end thereof, a reproducer headhaving a mounting element for firm coaction with the opposite end of said arm to efi'ect a p secure mechanical mounting connection, electric terminals at the side of said arm, and exible conductors carried by said head and having terminalsfor releasable coaction with lthe terminals on said arm. i

26. ln an electric phonograph reproducer, the combination of a channel shaped support arm, an electro-magnetic unit having bracket with a pilot portion straddled by the end of said arm, a screw in said arm retaining said pilot in place, and a stop screw in said arm retaining said pilot against movement about said rst screw.

27. lln an electric phonograph reproducer, the combination of a channel shaped support arm, an electro-magnetic unit having a bracket with a pilot portion straddled by the end of said arm, a screw releasably connecting said pilot in place an insulating sleeve about said screw, leads from the terminals of said unit, clamped against said pilot by said sleeve and sockets on-said arm for releasable connections therewith of the extremities of said leads.

vim

28. As an article of manufacture, a support ment thereof, resilient Plastic damper means engaging both sides o said armature, said damper means free from contact with the pole pieces, and means for bodily shifting said damper means in order to disposesaid armature in balanced position. Y

30. An electric phonograph reproducer, comprising magnetic pole pieces, an armature extending therebetween, mounting means for said armature governing the movement thereof, resilient plastic damper means engaging both sides of said arma-ture, said damper means free from contact with the pole pieces, a .metallic holder for said damper supported upon said pole pieces, and means accessible from the exteriorof the reproducer for ad- -justing the position of said holder andwith it of said damper and-armature.

3l. An electric'phonograph reproducer including magnetic pole pieces, an armature, and a resilient b/lock recessed to receive a portion of them-mature therein to center the armature, and means to bodily move the block to set the arma-ture, said means including an enclosing capsule for the block and a threadedadj listing screw associated therewith for moving the capsule upon rotation of the screw. v

Signed at New York city in the county of New York and State of New York.

MAXIMILIAN WEIL. 

